ISO 23828:2013

Fuel cell road vehicles - Energy consumption measurement - Vehicles fuelled with compressed hydrogen

ISO 23828:2013 specifies the procedures for measuring the energy consumption of fuel cell passenger cars and light-duty trucks that use compressed hydrogen and which are not externally chargeable.

Véhicules routiers avec pile à combustible — Mesurage de la consommation d'énergie — Véhicules alimentés par hydrogène comprimé

General Information

• Status: Withdrawn
• Publication Date: 14-Nov-2013
• ICS: 43.120 - Electric road vehicles
• Technical Committee: ISO/TC 22/SC 37 - Electrically propelled vehicles
• Drafting Committee: ISO/TC 22/SC 37 - Electrically propelled vehicles
• Current Stage: 9599 - Withdrawal of International Standard
• Start Date: 21-Jun-2022
• Completion Date: 13-Dec-2025

Relations

• Revised: ISO 23828:2022 - Fuel cell road vehicles - Energy consumption measurement - Vehicles fuelled with compressed hydrogen
• Effective Date: 23-Apr-2020
• Revises: ISO 23828:2008 - Fuel cell road vehicles - Energy consumption measurement - Vehicles fuelled with compressed hydrogen
• Effective Date: 26-Nov-2011

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 23828
Second edition
2013-11-15
Fuel cell road vehicles — Energy
consumption measurement — Vehicles
fuelled with compressed hydrogen
Véhicules routiers avec pile à combustible — Mesurage de la
consommation d’énergie — Véhicules alimentés par hydrogène
comprimé
Reference number
©
ISO 2013
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
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Published in Switzerland
ii © ISO 2013 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Measurement accuracy . 2
4.1 General . 2
4.2 Hydrogen measurement accuracy . 2
5 Hydrogen consumption measurement . 2
5.1 General . 2
5.2 Pressure method . 3
5.3 Gravimetric method . 3
5.4 Flow method . 3
6 Test conditions and instrumentation . 3
6.1 Test conditions . 3
6.2 Test instrumentation . 5
6.3 Fuel consumption tests . 5
6.4 Measurement and calculation over applicable driving test (ADT) . 5
6.5 Correction of the test results for FCHEV . 6
7 Presentation of results . 7
Annex A (informative) Test procedure in Japan. 8
Annex B (informative) Test procedure in Europe .12
Annex C (informative) Test procedure in the U.S.A. .16
Annex D (normative) Pressure method .22
Annex E (normative) Gravimetric method .24
Annex F (normative) Flow method .26
Annex G (informative) Current method .28
Annex H (informative) Determination of tank surface temperature measuring points .30
Annex I (informative) Test results of hydrogen consumption of test vehicle .34
Annex J (normative) Calculation of allowable range of RESS energy change .36
Annex K (normative) Linear correction method using a correction coefficient .38
Bibliography .40
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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committee has been established has the right to be represented on that committee. International
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
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For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 21,
Electrically propelled road vehicles.
This second edition cancels and replaces the first edition (ISO 23828:2008), which has been
technically revised.
iv © ISO 2013 – All rights reserved

INTERNATIONAL STANDARD ISO 23828:2013(E)
Fuel cell road vehicles — Energy consumption measurement
— Vehicles fuelled with compressed hydrogen
1 Scope
This International Standard specifies the procedures for measuring the energy consumption of fuel cell
passenger cars and light-duty trucks that use compressed hydrogen and which are not externally chargeable.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 10521 (all parts), Road vehicles — Road load
ISO 14687-2, Hydrogen fuel — Product specification — Part 2: Proton exchange membrane (PEM) fuel cell
applications for road vehicles
ISO/TR 8713, Electrically propelled road vehicles — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO/TR 8713 and the following apply.
3.1
applicable driving test
ADT
single driving test schedule which is specified for each region
EXAMPLE Chassis dynamometer test cycle for light-duty vehicles in Japan (JC08), New European Driving
Cycle (NEDC), Urban Dynamometer Driving Schedule (UDDS).
3.2
charge balance of battery
change of charge in battery during fuel consumption measurement
Note 1 to entry: Normally expressed in Ah.
3.3
energy balance of battery
ΔE
RESS
change of energy in battery during fuel consumption measurement
Note 1 to entry: Normally expressed in Wh.
Note 2 to entry: For practical use, the energy balance of a rechargeable energy storage system (RESS) is
approximated by multiplying the charge balance of battery in Ah by the nominal voltage in V. “Nominal voltage”
is defined in ISO 12405-1 or ISO 12405-2.
3.4
fuel cell hybrid electric vehicle
FCHEV
electrically propelled vehicle with a RESS and a fuel cell system as power sources for vehicle propulsion
3.5
fuel cell vehicle
FCV
electrically propelled vehicle with a fuel cell system as power source for vehicle propulsion
3.6
pure fuel cell vehicle
pure FCV
FCV with only a fuel cell system as power source for vehicle propulsion
3.7
rated capacity
supplier’s specification of the total number of ampere-hours that can be withdrawn from a fully charged
battery pack or system for a specified set of test conditions such as discharge rate, temperature,
discharge cut-off voltage, etc.
3.8
rechargeable energy storage system
RESS
system that stores energy for delivery of electric power and which is rechargeable
EXAMPLE Batteries, capacitors.
3.9
regenerative braking
braking with conversion of kinetic energy into electric energy for charging the RESS
3.10
state of charge
SOC
available capacity in a battery pack or system expressed as a percentage of rated capacity
4 Measurement accuracy
4.1 General
Measurement accuracy shall be in accordance with national standards.
4.2 Hydrogen measurement accuracy
Test apparatus shall ensure the accuracy of measurement of ±1 % for the total mass of hydrogen
consumption during the applicable driving test (ADT), unless otherwise specified in the relevant annexes.
5 Hydrogen consumption measurement
5.1 General
Hydrogen consumption shall be measured using one of the following:
— pressure method;
— gravimetric method;
— flow method.
2 © ISO 2013 – All rights reserved

5.2 Pressure method
Hydrogen consumption is determined by measuring the pressure and temperature of gas in the hydrogen
tank before and after the test. A tank with known internal volume that allows measurement of gas
pressure and temperature shall be used for the test. Pressure method shall be performed in accordance
with Annex D.
5.3 Gravimetric method
Hydrogen consumption is calculated by measuring the mass of the hydrogen tank before and after the
test. Gravimetric method shall be performed in accordance with Annex E.
5.4 Flow method
The amount of hydrogen supplied to a vehicle is measured by a flowmeter. Flow method shall be
performed in accordance with Annex F.
6 Test conditions and instrumentation
6.1 Test conditions
6.1.1 General
For test conditions, the following applies unless otherwise specified in the regional standards or
regulations (see Annex A, B, or C, for example).
6.1.2 Ambient temperature
Tests shall be conducted at an ambient temperature of (25 ± 5) °C.
6.1.3 Vehicle conditions
6.1.3.1 Vehicle conditioning
Prior to testing, the test vehicle shall be stabilized; this includes vehicle mileage accumulation in
accordance with a manufacturer-determined distance, unless otherwise specified in Annex A, B, or C.
6.1.3.2 Vehicle appendages
Vehicles shall be tested with normal appendages (mirrors, bumpers, etc.). When the vehicle is on the
dynamometer, certain items (e.g. hub caps) should be removed for reasons of safety, where necessary.
6.1.3.3 Vehicle test mass
The vehicle test mass shall be selected according to the regional standards and/or regulations (see
Annex A, B, or C, for example).
6.1.3.4 Tyres
6.1.3.4.1 General
The correctly rated tyres as recommended by the vehicle manufacturer shall be used.
6.1.3.4.2 Tyre pressure
The vehicle tyres shall be inflated to the pressure specified by the vehicle manufacturer according to the
test chosen (track or chassis dynamometer).
6.1.3.4.3 Tyre conditioning
The tyres shall be conditioned as recommended by the vehicle manufacturer.
6.1.3.5 Lubricants
The vehicle lubricants normally specified by the manufacturer shall be used.
6.1.3.6 Gear shifting
If the vehicle is fitted with a manually shifted gear box, gear shifting positions shall correspond to
the regional test procedure (see Annex A, B, or C, for example). However, the shift positions should be
selected and determined in accordance with the vehicle manufacturer’s specification.
6.1.3.7 Regenerative braking
If the vehicle has regenerative braking, the regenerative braking system shall be enabled for all
dynamometer testing except where specified in 6.1.4.4 chassis dynamometer conditions.
If the vehicle is tested on a single axle dynamometer and is equipped with systems such as an antilock
braking system (ABS) or a traction control system (TCS), those systems can inadvertently interpret
the non-movement of the set of wheels that are off the dynamometer as a malfunctioning system. If so,
these systems shall be temporally disabled for adjustment to achieve normal operation of the remaining
vehicle systems, including the regenerative braking system.
6.1.3.8 RESS conditioning
The RESS shall be conditioned with the vehicle as specified in 6.1.3.1 or by equivalent conditioning.
6.1.3.9 Test fuel
ISO 14687-2 and the equivalent regional standards shall apply to test fuel.
6.1.4 Chassis dynamometer conditions
6.1.4.1 General
The vehicle should generally be tested on a single-axle chassis dynamometer. A vehicle with four-wheel
drive shall be tested by modifying the drive train of the vehicle. When the vehicle is modified, the details
shall be explained in the test report.
Double-axle chassis dynamometer testing should be performed if a modification for single-axle chassis
dynamometer testing is not possible for a specific four-wheel drive vehicle.
6.1.4.2 Dynamometer calibration
The dynamometer shall be calibrated in accordance with the specifications indicated in the service
manual provided by the dynamometer manufacturers.
6.1.4.3 Dynamometer warm-up
The dynamometer shall be warmed up sufficiently prior to testing.
4 © ISO 2013 – All rights reserved

6.1.4.4 Determining the dynamometer load coefficient
The determination of vehicle road load and the reproduction on a chassis dynamometer shall conform
to ISO 10521. Vehicles equipped with regenerative braking systems that are activated at least in part
when the brake pedal is not depressed shall have regenerative braking disabled during the deceleration
portion of coast-down testing on both the test track and dynamometer.
6.2 Test instrumentation
Test instrumentation shall have accuracy levels as shown in Table 1, unless specified differently in
Annex A, B, or C.
Table 1 — Accuracy of measured values
Item Unit Accuracy
Time s ±0,1 s
Distance m ±0,1 %
Temperature °C ±1 °C
Speed km/h ±1 %
Mass kg ±0,5 %
Current A ±0,5 %
Capacitor voltage V ±0,5 % of nominal voltage
6.3 Fuel consumption tests
6.3.1 General
Depending on the region concerned, the appropriate procedure shall be followed from Annex A, B, or C.
Details and common procedures for each test mode are described below.
6.3.2 Vehicle preconditioning
Vehicle preconditioning shall be carried out in accordance with the annex appropriate for the region. In
the case of FCHEV, the RESS state of charge can be pre-adjusted by charging or discharging, to obtain a
suitable energy difference in RESS between the start and the end of test.
6.3.3 Vehicle soak
The vehicle shall be soaked in accordance with the appropriate regional procedure prescribed in
Annex A, B, or C.
6.3.4 Vehicle movement to the test room
When the vehicle is brought into the test room, and moved during the test if necessary, it shall be
pushed or towed (neither driven nor regenerative recharged). The test vehicle shall be set on the chassis
dynamometer after the chassis dynamometer has warmed up just before the test. The vehicle shall not
be activated during soak until right before starting the test.
6.4 Measurement and calculation over applicable driving test (ADT)
For the measurement of hydrogen consumption, the test vehicle shall be driven on the chassis
dynamometer in accordance with the ADT prescribed for the region (see Annex A, B, or C). The hydrogen
consumption shall be measured by one of the methods described in Annex D, E, or F or by an alternative
method that provides equivalent accuracy.
The hydrogen consumption per unit distance is determined by means of one of the following formulae:
22,414
−3
−3 w××10
b × 10
t0 m
C == (1)
F1
L L
m
−3
b ××10
−3
t0
w×10
22,414
C = = (2)
F2
L L
22,414
−3
−3 w××10 ×Q
H
bQ××10
tH0 m
C = = (3)
F3
L L
where
is the hydrogen consumption per unit distance, in m /km, referred to volume at normal
C
F1
conditions (273 K; 101,3 kPa);
C is the hydrogen consumption per unit distance, in kg/km, referred to mass;
F2
C is the hydrogen consumption per unit distance, in MJ/km, referred to caloric value;
F3
L
is the distance, in km;
b is the hydrogen consumption at normal conditions in l (273 K, 101,3 kPa);
t0
w
is the hydrogen consumption, in g;
m
is the molecular mass of hydrogen (2,016);
Q is the lower calorific value of hydrogen (10,8 MJ/Nm ).
H
6.5 Correction of the test results for FCHEV
6.5.1 General
Measured hydrogen consumption shall be corrected if these test results are influenced by RESS energy
balance during the test. However, the correction is not necessary if the RESS energy balance satisfies
the conditions in 6.5.2.
6.5.2 Allowable range of RESS energy balance
The correction of the test results is not necessary for the following range of the RESS energy balance:
||ΔEE≤×00, 1 (4)
RESS CF
where
ΔE is the energy change in RESS over the ADT;
RESS
E is the energy of consumed fuel over the ADT.
CF
ΔE shall be calculated in accordance with Annex J.
RESS
6 © ISO 2013 – All rights reserved

6.5.3 Correction procedure by correction coefficient
The vehicle manufacturer shall deliver the correction coefficient to calculate the fuel consumption at
ΔE = 0. The correction coefficient can be obtained in accordance with Annex K. When the measured
RESS
value is independent of ΔE , a correction is not required.
RESS
7 Presentation of results
Test results should be recorded in accordance with the regional regulations. See Annex I for example.
Annex A
(informative)
Test procedure in Japan
A.1 General
Annex A describes the procedures and related conditions in Japan (JC08-mode) to measure the fuel
consumption of the passenger cars and light-duty trucks defined in Japan regulations.
Japan Regulations are written as “Announcement that Prescribes Details of Safety Regulations for Road
Vehicles (Ministry of Land, Infrastructure, Transport and Tourism [MLIT] Announcement No. 619,
2002;) Attachment 42”, “TRIAS 99-006”, and “TRIAS 31-J042(3)”.
A.2 Test
A.2.1 Chassis dynamometer
The equivalent inertia mass of the chassis dynamometer shall be set to the standard value of equivalent
inertia mass specified in the right column of Table A.1 according to the relative test vehicle mass (vehicle
curb mass plus 110 kg) specified in the left column of the table. Furthermore, if the standard value of the
equivalent inertia mass in the right column of the table cannot be set, it is permissible to set the equivalent
inertia mass within a range between the said standard value and the said standard value plus 10 %.
A.2.2 Applicable driving test (ADT)
The test vehicle shall run the applicable driving test (ADT). In Japan, JC08-mode driving schedule [0s to
1204s] specified in Japan Regulations is applicable (see Figure A.1).
A.2.3 Test vehicle mass
Test vehicle mass at measuring running resistance and at measuring fuel consumption on the chassis
dynamometer shall be vehicle curb mass plus 110 kg.
A.3 Test procedure
A.3.1 General
Preconditioning shall be performed on the chassis dynamometer after given road load setting. Then, the
test procedure shall be carried out according to the test flow in Figure A.2 or A.3.
A.3.2 Cold start JC08 mode (JC08CM)
In the case of cold start, the test starts immediately after the specified soak procedure (see A.1). Test
flow in Figure A.2 is applicable.
A.3.3 Hot start JC08 mode (JC08HM)
In the case of hot start, the vehicle is under warmed-up condition. Test flow in Figure A.3 is applicable.
8 © ISO 2013 – All rights reserved

A.4 Calculation of fuel consumption test procedure
The measured hydrogen consumption shall be calculated to the required unit value. See 6.4.
Table A.1 — Test vehicle mass and standard value of equivalent inertia mass
Test vehicle mass (kg) Standard value of equivalent inertia mass (kg)
~ 480 455
481 ~ 540 510
541 ~ 595 570
596 ~ 650 625
651 ~ 710 680
711 ~ 765 740
766 ~ 850 800
851 ~ 965 910
966 ~ 1 080 1 020
1 081 ~ 1 190 1 130
1 191 ~ 1 305 1 250
1 306 ~ 1 420 1 360
1 421 ~ 1 530 1 470
1 531 ~ 1 640 1 590
1 641 ~ 1 760 1 700
1 761 ~ 1 870 1 810
1 871 ~ 1 980 1 930
1 981 ~ 2 100 2 040
2 101 ~ 2 210 2 150
2 211 ~ 2 380 2 270
2 381 ~ 2 625 2 500
2 626 ~ 2 875 2 750
2 876 ~ 3 250 3 000
3 251 ~ 3 750 3 500
Continued in increments of 500 kg Continued in increments of 500 kg
Annex B
(informative)
Test procedure in Europe
B.1 General
Based on the legal requirements in Europe, Annex B specifies the specific preconditioning procedures
and relevant test equipment for the determination of hydrogen consumption of pure FCV and FCHEV non-
externally chargeable and with FCHEV mode only of categories M1 and N1 with a maximum permissible
total mass (in accordance with ISO 1176) of 3 500 kg.
NOTE 1 The outline given in Annex B contains only those elements essential to understanding the procedure.
For further details, reference is made to the relevant clauses and subclauses in the regulations UNECE R 101
and UNECE R 83.
NOTE 2 Annex B is based on the following editions of the two regulations:
- UNECE R 101: Trans/WP.29/GRPE/2004/2, 30 October 2003;
- UNECE R 83: E/ECE/324 Rev.1/Add.82/Rev.2 E/ECE/Trans/505, 30 October 2001.
It does not necessarily reflect subsequent amendments to UNECE R 101 and UNECE R 83.
B.2 Test equipment
B.2.1 Chassis dynamometer
Features, accuracy, load and inertia setting, calibration, and other steps to prepare the chassis
dynamometer to be used are prescribed in UNECE R 83, Annex 4, 4.1, 5.1, and 5.2 and in Appendices 2
and 3 of Annex 4. The adjustment of the inertia simulators to the vehicle’s translatory inertias shall be
in accordance with Table B.1 (as given in UNECE R 83, Annex 4, 5.1).
Table B.1 — Equivalent inertia of the dynamometer related to the reference mass of the vehicle
Reference mass of the vehicle RW (kg) Equivalent inertia (kg)
RW ≤ 480 455
480 < RW ≤ 540 510
540 < RW ≤ 595 570
595 < RW ≤ 650 625
650 < RW ≤ 710 680
710 < RW ≤ 765 740
765 < RW ≤ 850 800
850 < RW ≤ 965 910
965 < RW ≤ 1 080 1 020
1 080 < RW ≤ 1 190 1 130
1 190 < RW ≤ 1 305 1 250
1 305 < RW ≤ 1 420 1 360
1 420 < RW ≤ 1 530 1 470
12 © ISO 2013 – All rights reserved

Table B.1 (continued)
Reference mass of the vehicle RW (kg) Equivalent inertia (kg)
1 530 < RW ≤ 1 640 1 590
1 640 < RW ≤ 1 760 1 700
1 760 < RW ≤ 1 870 1 810
1 870 < RW ≤ 1 980 1 930
1 980 < RW ≤ 2 100 2 040
2 100 < RW ≤ 2 210 2 150
2 210 < RW ≤ 2 380 2 270
2 380 < RW ≤ 2 610 2 270
2 610 < RW 2 270
B.2.2 Test equipment for hydrogen measurement methods
For specific test equipment for the hydrogen measurement methods, see Clause 5 and Annexes D, E, and F.
B.3 Test vehicle
B.3.1 General
The test vehicle shall be in running order, as determined by the manufacturer, with all the equipment
provided as standard.
B.3.2 Test mass
The mass of the vehicle under test (referred to as “reference mass” in UNECE R 83, 2.2) shall be the
“unloaded mass” plus a uniform figure of 100 kg. The “unloaded mass” (see UNECE R 83, 2.2.1) is the
mass of the vehicle in running order, without load and persons, but with the hydrogen tank 90 % full.
B.3.3 Tyres
The tests shall be performed with standard width tyres, as provided by the vehicle manufacturer.
Alternatively, the prescription of UNECE R 83, Annex 4, Appendix 3, 4.1.2, can be applied, i.e. only the
widest of the standard widths or the widest minus one (in case of more than three standard widths)
shall be chosen.
The tyre pressure shall comply with the vehicle manufacturer specification, but can be increased by
up to 50 % when the test is carried out on a two-roller dynamometer (see UNECE R 83, Annex 4, 5.3.2).
B.4 Test cycle
The test cycle to be applied shall be the same as that prescribed for the Type I test. This test, including
allowable tolerances, is described in UNECE R 83, Annex 4, Appendix 1.
The test cycle is made up of one Part 1 (urban) cycle, consisting of four elementary urban cycles, and one
Part 2 (extra-urban) cycle, as illustrated roughly in Figure B.1 and described in Table B.2.
Key
X time, s
Y vehicle speed, km/h
1 part 1, urban cycle
2 part 2, extra-urban cycle
3 elementary urban cycle
Figure B.1 — Test cycle
Table B.2 — General information on the test cycle
Urban cycle Extra-urban
cycle
Average speed 19 km/h 62,6 km/h
Max. speed 50 km/h 120 km/h
Effective running 4 × 195 s = 780 s 400 s (6 min,
time (13 min) 40 s)
B.5 Test procedure
B.5.1 Preconditioning of the vehicle
The vehicle shall be stabilized in accordance with the vehicle manufacturer’s specification, followed by
two consecutive full test cycles (see B.4).
B.5.2 Conditioning of the vehicle
After preconditioning in accordance with B.5.1, the vehicle shall be kept in a room with a relative constant
temperature of between 20 °C and 30 °C for at least 6 h, until the lubricant and coolant temperatures are
14 © ISO 2013 – All rights reserved

within ±2 °C of the room temperature. If requested by the manufacturer, the test shall be carried out not
later than 30 h after the vehicle has been run at its normal temperature.
B.5.3 Performance of the test
B.5.3.1 General
After preconditioning and conditioning in accordance with B.5.1 and B.5.2, respectively, one complete
test cycle shall be run in accordance with B.4. The test equipment shall comply with B.2 and the test
vehicle shall comply with B.3. The following requirements shall also be met during the test.
B.5.3.2 Additional conditions
The temperature shall be between 20 °C and 30 °C and the absolute humidity between 5,5 g and 12,2 g
H O/kg dry air.
B.5.3.3 Performing the different steps of the test cycle
The test shall be performed in accordance with the prescriptions of the vehicle manufacturer, starting with
the activation of the propulsion system and followed by applying the test cycle. To match the allowable
tolerances of the test cycle, the procedure recommended by the vehicle manufacturer should be applied.
The hydrogen consumption shall be measured using one of the methods described in Clause 5 and Annexes D,
E, and F, respectively. In the case of FCHEV, it shall be corrected, in accordance with 6.5, if necessary.
Annex C
(informative)
Test procedure in the U.S.A.
C.1 Background
Annex C describes the test procedure recommended for use in the USA and in other countries that use
SAE (Society of Automotive Engineers, Inc.) methods for measuring fuel consumption and range of FCV
and FCHEV fuelled by compressed gaseous hydrogen. Annex C makes reference to SAE J2572: 2006 as
the specific governing document.
C.2 General
Annex C prescribes the uniform chassis dynamometer test procedures for FCV and FCHEV designed to
be driven on public roads. Low-speed vehicles are not covered in Annex C. Instructions are given for
measuring and calculating the fuel consumption and range using two test types:
— the “city” fuel consumption test using the Urban Dynamometer Driving Schedule (UDDS) and
— the “highway” fuel consumption test using the Highway Fuel Economy Driving Schedule (HFEDS).
Annex C covers only FCV fuelled with compressed gaseous hydrogen and FCHEV, also fuelled with
compressed gaseous hydrogen, and which have a rechargeable energy storage system (RESS) (battery
or capacitor).
C.3 General test information
C.3.1 Driving schedules
The driving schedules to be used for vehicle testing provided by the United States Environmental Protection
Agency (EPA) are the Urban Dynamometer Driving Schedule (UDDS) and the Highway Fuel Economy
Driving Schedule (HFEDS). The City Fuel Economy Test, which uses the UDDS, is detailed in SAE J2572:
2006, 6.1. The Highway Fuel Economy Test, which uses the HFEDS, is detailed in SAE J2572: 2006, 6.2.
C.3.2 Battery state of charge
If the net energy of the battery/capacitor system increases or decreases by less than or equal to 1 % of
the total hydrogen energy consumed by the vehicle during the course of the test, the application of a
correction equation is not necessary, i.e. no correction calculation is necessary if
ΔStored electricalenergy
≤ 1% (C.1)
Totalfuelenergyc onsumed
where both the change in stored electrical energy (ΔE ) and the total fuel (H ) energy consumed,
RESS 2
reported to one decimal point (e.g. 0,1 g), are expressed in units of energy (J). The lower net heating
value for hydrogen gas is used to convert the total hydrogen consumed into units of Ah, using a factor
of 120 000 J/g.
16 © ISO 2013 – All rights reserved

Expressed in terms of the energy content of hydrogen per unit of mass, the calculation is as follows:
||ΔEM≤×00, 1 ×120000 (C.2)
RESS
where
M is the total mass of hydrogen consumed over each phase of the test (M , M , M ),
UDDS1 UDDS2 HWFET
in g.
All mass values are reported to the nearest 0,1 g.
All distances are reported to the third decimal place (0,001 km).
All fuel consumption values are reported to the nearest 0,000 1 kg/km.
C.4 Test requirements
C.4.1 Vehicle condition
C.4.1.1 General
Prior to initiation of testing and during testing, the overall condition and configuration of the vehicle shall
be as delineated in SAE J2572: 2006, 4.1 and subsequent subclauses, all of which are represented below.
C.4.1.2 Vehicle stabilization
Prior to testing, the test vehicle shall be stabilized as determined by the manufacturer to a minimum of
1 609 km (1 000 miles), but not more than 9 978 km (6 200 miles) using the durability driving schedule
specified in CFR Title 40, Part 86, Appendix IV, section (a), or an equivalent schedule. For all preparations
and testing, hydrogen complying with fuel specified by the SAE or the appropriate US government
agency shall be used and that fuel shall comply with the fuel quality guidance specified in SAE J2719.
C.4.1.3 Vehicle appendages
Vehicles shall be tested with normal appendages (mirrors, bumpers, etc.). Certain items (e.g. hub caps)
can be removed where necessary for safety on the dynamometer. If an off-board fuel source is used for
the test, the test vehicle can include a connector to receive the fuel from that source.
C.4.1.4 Accessories
All accessories shall be turned off.
C.4.1.5 Vehicle test mass
The vehicle shall be tested at loaded vehicle weight (curb weight plus 136 kg [300 lb]).
C.4.1.6 Tyres
Manufacturer’s recommended tyres shall be used. For dynamometer testing, tyre pressures should be
set at the beginning of the test at the pressure used to establish the dynamometer road-load coefficients
(see C.4.3) and shall not exceed levels necessary for safe operation. Tyres shall be conditioned as
recommended by the vehicle manufacturer, have accumulated a minimum of 100 km (62 miles), and
have at least 50 % of the original usable tread depth remaining.
C.4.1.7 Lubricants
The vehicle lubricants normally specified by the manufacturer shall be used.
C.4.1.8 Regenerative braking
If the vehicle has regenerative braking, the regenerative braking system shall be enabled for all chassis
dynamometer testing, except for track coast down testing. If the regenerative braking level is adjustable,
it shall be set in accordance with the manufacturer’s specification prior to starting dynamometer testing.
Operation of the regenerative braking system shall not cause speed and time tolerances specified by the
test driving schedule to be exceeded.
C.4.1.9 Vehicle capability
The test vehicle shall be able to maintain the speed and distance tolerances required by the UDDS and
HFEDS schedules.
C.4.1.10 Fuel cell stack condition
The stack shall have been aged with the vehicle as detailed in C.4.1.2, or equivalent conditioning.
C.4.1.11 Propulsion battery/capacitor condition
The propulsion system battery/capacitor shall have been aged with the vehicle, as detailed in C.4.1.2,
or equivalent conditioning. The vehicle shall have an access point for measurement of current readings
into and out of the energy storage device. Reading from a vehicle onboard current measurement system
can be used provided that ±1 % NIST (National Institute of Standards and Technology) traceability can
be demonstrated.
C.4.2 Environmental conditions
All test sequences shall be conducted with an ambient temperature within the range of 20 °C to 30 °C
(68 °F to 86 °F).
C.4.3 Dynamometer
Use of an electric 48-inch single roll chassis dynamometer, or equivalent, is required for FCV and FCHEV
testing. All factors concerning the dynamometer, specifically its capability requirements, configuration,
calibration, warm-up, and settings, are presented in SAE J2572: 2006, 4.5 and subsequent subclauses, and
these give further reference to other specific requirements as contained in CFR Title 40, Part 86, section
135-90 (i). The determination of the dynamometer load coefficients shall be as specified in SAE J2264.
C.4.4 Instrumentation
All instrumentation requirements for the test, including the list of instruments and instrument accuracy
requirements, are presented in SAE J2572: 2006, 4.6 and subsequent subclauses. All instrumentation
calibration must be NIST traceable to within ±1,0 % of the full scale of the appropriate range.
C.5 Required data collection
The data that must be collected regarding the vehicle, test conditions, instrumentation, fuel consumed
and the dynamometer type, settings, and results are detailed in SAE J2572: 2006, 5.1, 5.2, and
subsequent subclauses.
18 © ISO 2013 – All rights reserved

C.6 Testing the vehicle
C.6.1 General
The driving schedules provided by the U.S. Environmental Protection Agency (EPA) are used for the tests.
C.6.2 City fuel economy test
The driving cycle used for the city fuel economy test, illustrated in Figure C.1, represents US city driving
and consists of a series of non-repetitive idle, acceleration, cruise, and deceleration modes of various
time sequences throughout an interval of 1 372 s, as detailed in the EPA Urban Dynamometer Driving
Schedule (UDDS). Full detail is provided in SAE J2572:2006, 6.1. Specific speed tolerance and fuel
consumption considerations for the test sequence are presented in SAE J2572:2006, 6.3 and 6.4.
Y
0 200 400 600 800 1 000 1 200 1 400
X
Key
X time, s
Y vehicle speed, mph
Figure C.1 — Driving cycle used for the city fuel economy test
C.6.3 Highway fuel economy test
The driving cycle used for the highway fuel economy test, illustrated in Figure C.2, represents US
highway driving and consists of a series of non-repetitive acceleration, cruise, and deceleration modes
of various time sequences throughout an interval of 765 s, as detailed in the EPA Highway Fuel Economy
Driving Schedule (HFEDS). Full detail is provided in SAE J2572: 2006, 6.2. Specific speed tolerance and
fuel consumption considerations for the test sequence are presented in SAE J2572: 2006, 6.3 and 6.4.
Y
0 100 200 300 400 500 600 700 800
X
Key
X time, s
Y vehicle speed, mph
Figure C.2 — Driving cycle used for the highway fuel economy test
C.7 Vehicle fuel consumption
C.7.1 Test method
Fuel consumed by a vehicle under test is determined by operating the vehicle on a dynamometer using
prescribed driving cycles.
C.7.2 Measurement of fuel consumption
The fuel consumed is reported as the mass quantity of hydrogen consumed per distance travelled,
specifically as kg/km. Three methods are available for determining the net change in mass of hydrogen
during testing:
— the stabilized pressure and temperature for a fixed volume pressure vessel taken before and
after each test,
— the gravimetric method for weighing auxiliary fuel tanks, and
— the use of an appropriate fuel flowmeter.
These three methods are presented in detail in SAE J2572: 2006, 7.2.1, 7.2.2, and 7.2.3, respectively.
C.7.3 Calculation of fuel consumption rate
Formulae 2 and 3 in SAE J2572: 2006, 7.3 are used to calculate fuel consumption, expressed in kg/km,
for city driving and for highway driving, respectively.
C.7.4 Dynamometer coefficients
Dynamometer target coefficients are to be determined as prescribed in SAE J2264.
20 © ISO 2013 – All rights reserved

C.7.5 Dynamometer test procedure for city fuel consumption measurement
All specifics of the test procedure, including fuelling, temperature stabilization, vehicle preparation and
preconditioning, dynamometer preparation, etc., as well as the details of the tests to be conducted, are
presented in SAE J2572: 2006, 7.5.1 to 7.5.13.
C.7.6 Dynamometer test procedure for highway fuel economy measurement
All specifics of the test procedure, including fuelling, temperature stabilization, vehicle preparation,
dynamometer preparation, etc., as well as the details of the tests to be conducted, are presented in
SAE J2572: 2006, 7.6.1 to 7.6.13.
C.7.7 Fuel consumption calculation correction to account for battery/capacitor effect
For FCHEV, a method is provided to correct for the battery/capacitor influence on fuel consumption
for the case where the final system state of charge has increased or decreased by more than 1 % from
the initial system state of charge. For the case where there is an increase in battery/capacitor energy
at the end of a test, the manufacturer has the option not to apply the correction calculation. Details of
the calculation methods are presented in SAE J2572: 2006, 7.7 and subsequent subclauses, for a FCHEV
equipped with a battery system, for the city (UDDS) test, and for the highway (HFEDS) test, as well as
for the case of a hybrid vehicle equipped with a capacitor system.
C.8 Calculation of vehicle range
C.8.1 General
The driving range of a FCV and of a FCHEV is determined from the testing and calculation methods used
to develop the fuel consumption information.
C.8.2 City range
City range, expressed in km, is determined by dividing the usable fuel amount (the difference in mass
between the total fuel capacity and the unusable fuel amount) by the city fuel consumption (from
SAE J2572: 2006, 7.3, Formula 2). [See CFR Title 40, Part 600, section 209-95 (a)(2)(i) regarding US
labelling purposes.]
C.8.3 Highway range
Highway range, reported in kilometres, is determined by dividing the usable fuel amount by the corrected
highway fuel consumption (from SAE J2572: 2006, 7.3, Formula 3). [See CFR Title 40, Part 600, section
209-95 (b)(2)(i) regarding US labelling purposes.]
C.8.4 Combined range
Combined range, reported in kilometres, is determined by dividing the usable fuel amount contained in
the fuel tank by the combined fuel consumption. [See CFR Title 40, Part 600, section 209-95 (d)(2)(i).]
Annex D
(normative)
Pressure method
An example of instrumentation is shown in Figure D.1. An additional tank is used to measure the
hydrogen consumption. The additional tank shall be connected to the vehicle.
For preconditioning, the originally installed tank or an external source of hydrogen shall be used as
shown in Figure D.1.
The refuelling pressure of the additional tank shall be adjusted according to the manufacturer’s
recommended values.
The following items are given as requirements for the additional tank. The internal volume of the tank
and accessories (hydrogen lines, for example) upstream of the pressure regulator shall be known.
A means to measure the internal gas pressure and gas temperature shall be available. The volume
change of the additional tank during the test shall be small enough not to affect the test result.
NOTE If gas temperature cannot be measured directly, an alternative method can be used, e.g. as described
in Annex H.
Key
1 external hydrogen supply
2 pressure regulator
3 original tank
4 fuel cell system
5 temperature gauge
6 additional tank
Figure D.1 — Example of instrumentation
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